package com.moyoutian.leetcode;

/**
 *104. 二叉树的最大深度
 * 给定一个二叉树，找出其最大深度。
 *
 * 二叉树的深度为根节点到最远叶子节点的最长路径上的节点数。
 *
 * 说明: 叶子节点是指没有子节点的节点。
 *
 * 示例：
 * 给定二叉树 [3,9,20,null,null,15,7]，
 *
 *     3
 *    / \
 *   9  20
 *     /  \
 *    15   7
 * 返回它的最大深度 3 。
 *
 * 通过次数500,988提交次数653,972
 */
public class Demo104 {


    public static class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }


    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        System.out.println(maxDepth(root));
        root.left = new TreeNode(0);
        System.out.println(maxDepth(root));
        root.right = new TreeNode(2);
        System.out.println(maxDepth(root));
        root.left.left = new TreeNode(-1);
        System.out.println(maxDepth(root));
        root.left.right = new TreeNode(2);
        System.out.println(maxDepth(root));
        root.right.left = new TreeNode(-1);
        System.out.println(maxDepth(root));
        root.right.right = new TreeNode(2);
        System.out.println(maxDepth(root));
        root.right.right = new TreeNode(-1);
        System.out.println(maxDepth(root));
        root.right.right = new TreeNode(2);
        System.out.println(maxDepth(root));
    }


    public static int maxDepth(TreeNode root) {

        return maxDepth(root, 0);
    }

    public static int maxDepth(TreeNode root, int i) {
        if (root == null) {
            return 0;
        }
        return 1 + Math.max(maxDepth(root.left, i + 1), maxDepth(root.right, i + 1));
    }
}
